Linear actuators are well known and have been in use for a long time. However, actuators which have been developed for use in the field of airflow control service have generally been pneumatic. Pneumatic actuators are characterized by their slow response time and as a result, the actuator is often the "bottleneck" in the airflow control loop.
In an effort to improve actuators, attempts have been made at designing an electronically based actuator. The few electric actuators which have been sold in the damper market have been off-on time proportioning with AC drives. They have not controlled airflow well as time proportioning is a poor choice for control action when the system response is fast, such as for airflow. In addition, these prior art devices have had a high failure rate which is probably due to cost constraints imposed during design in order to make the product competitive with other available technologies.
Accordingly, it is an object of the present invention to provide a new and improved linear actuator with improved reliability and accuracy.
Another object of the present invention is to provide a linear actuator which lacks one or more of the shortcomings of the previously proposed systems.
A further object of the present invention is to provide a linear actuator which is electronic.
A still further object of the present invention is to provide a linear actuator having fast response time.
Yet another object of the present invention is to provide a linear actuator with low hysteresis.
An additional object of the present invention is to provide a linear actuator which delivers high performance at low cost.